U.S. Pat. No. 4,459,352 discloses aqueous coating compositions for forming conductive layers in composite bases or elements, particularly photographic elements having hydrophobic supports. The coating compositions therein described are comprised of (i) an ester of cellulose having at least 8 acyl groups per C.sub.24 cellulose unit, wherein at least a majority of the acyl units are derived from an aliphatic carboxylic acid having from 3 to 6 carbon atoms, or (ii) a salt of such an ester.
This invention relates to an improvement of the invention of U.S. Pat. No. 4,459,352. More specifically, this invention relates to improved esters and salts of the type defined above. Specifically, such esters and salts are made from a cellulose derived (a) from an acylated cellulose starting material such as cellulose acetate, by (b) conducting the deacylation reaction using an alkali metal alkoxide as a catalyst, and an alcohol as the deacylative reagent. Preferably, the reaction is conducted using methanol and sodium methoxide.
It is known that cellulose acetate can be deacylated in this manner, see Research Disclosure No. 176, 17624 (December 1978); U.S. Pat. No. 3,950,282 see column 10, lines 55-60, Manley, J. of Polymer Science: Part A, Vol 1, pp 1893-1899 (1963); Wadehra et al, J. of Applied Polymer Science, vol 9, pp 2627-2630 (1965); Sisson, Industrial and Engineering Chemistry, 30, No. 5 pp 530-537, (may 1938), and Jeffries, J. of Applied Polymer Science, Vol 12, pp 425-445 (1963).
None of these references relate to the hydrogen cellulose esters or the salts thereof that are provided by this invention.